Liquid phase separation of proteins based on electrophoretic effects in an electrospray setup during sample introduction into a gas-phase electrophoretic mobility molecular analyzer (CE-GEMMA/CE-ES-DMA).
Bottom Line: This makes the EM determination of individual species sometimes difficult, if not impossible.This finding was consecutively applied for on-line desalting allowing EM diameter determination of analytes despite a high salt concentration within samples.Results demonstrate the proof of concept of such an approach and additionally illustrate the high potential of a future on-line coupling of a capillary electrophoresis to a GEMMA instrument.
Affiliation: Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria.Show MeSH
Related in: MedlinePlus
Mentions: Results from on-line desalting in the nano ES capillary of the GEMMA instrument (addition of 5 mmol L−1 sodium chloride to a mixed BSA/IgG sample in ammonium acetate) are depicted in Fig. 6, together with results for the same sample obtained in NM. GEMMA experiments in NM exhibit results shown in Fig. 6(A) (for samples) and Fig. 6(B) (for blanks), dashed lines, respectively. For comparison reasons also spectra recorded in the absence of sodium chloride (solid lines) are shown. Addition of sodium chloride leads to a massive increase in the background signal (Fig. 6(B)) due to salt aggregation in droplets generated by the nano ES process and their subsequent detection as residue particles. Concurrently, also aggregates between proteins and salt molecules are recorded. Whereas the IgG peak maximum shifts to higher EM diameter values by about 6% due to an unwanted salt crust formation around the protein, BSA can be no longer detected due to the increased background signal. Additionally, the IgG peak also increases in peak width as a result from heterogeneous protein/salt aggregates.
Affiliation: Institute of Chemical Technologies and Analytics, Vienna University of Technology, Vienna, Austria.